Back to the Fifties With AC/DC

"It was amazing! I have to tell you about the entire trip!" exclaimed Tinman, the town lunatic.
"I was tinkering around with my microwave, because it's always breaking down. Suddenly, right after I connected two wires, I was shot into a white abyss where I was brought back to the year 1950. When I was walkin' around I noticed there was a concert goin' on. I went inside and eventually I got to play. It was so amazing! I went up there and started playing AC/DC. The people were so amazed, probably because they've never heard distortion like that before!" Then, someone said that he was lying and told everyone how that would be impossible. What did he use as proof?